NAME¶
multiplexer - One-to-many communication with sockets.
SYNOPSIS¶
package require
Tcl 8.2
package require
logger
package require
multiplexer ?0.2?
::multiplexer::create
${multiplexer_instance}::Init port
${multiplexer_instance}::Config key value
${multiplexer_instance}::AddFilter cmdprefix
cmdprefix data chan clientaddress clientport
${multiplexer_instance}::AddAccessFilter cmdprefix
cmdprefix chan clientaddress clientport
${multiplexer_instance}::AddExitFilter cmdprefix
cmdprefix chan clientaddress clientport
DESCRIPTION¶
The
multiplexer package provides a generic system for one-to-many
communication utilizing sockets. For example, think of a chat system where one
user sends a message which is then broadcast to all the other connected users.
It is possible to have different multiplexers running concurrently.
- ::multiplexer::create
- The create command creates a new multiplexer 'instance'. For
example:
set mp [::multiplexer::create]
- This instance can then be manipulated like so:
- ${multiplexer_instance}::Init port
- This starts the multiplexer listening on the specified port.
- ${multiplexer_instance}::Config key value
- Use Config to configure the multiplexer instance. Configuration
options currently include:
- sendtoorigin
- A boolean flag. If true, the sender will receive a copy of the sent
message. Defaults to false.
- debuglevel
- Sets the debug level to use for the multiplexer instance, according to
those specified by the logger package (debug, info, notice, warn,
error, critical).
- ${multiplexer_instance}::AddFilter cmdprefix
- Command to add a filter for data that passes through the multiplexer
instance. The registered cmdprefix is called when data arrives at a
multiplexer instance. If there is more than one filter command registered
at the instance they will be called in the order of registristation, and
each filter will get the result of the preceding filter as its argument.
The first filter gets the incoming data as its argument. The result
returned by the last filter is the data which will be broadcast to all
clients of the multiplexer instance. The command prefix is called as
- cmdprefix data chan clientaddress
clientport
- Takes the incoming data, modifies it, and returns that as its
result. The last three arguments contain information about the client
which sent the data to filter: The channel connecting us to the client,
its ip-address, and its ip-port.
- ${multiplexer_instance}::AddAccessFilter cmdprefix
- Command to add an access filter. The registered cmdprefix is called
when a new client socket tries to connect to the multixer instance. If
there is more than one access filter command registered at the instance
they will be called in the order of registristation. If any of the called
commands returns -1 the access to the multiplexer instance is
denied and the client channel is closed immediately. Any other result
grants the client access to the multiplexer instance. The command prefix
is called as
- cmdprefix chan clientaddress clientport
- The arguments contain information about the client which tries to
connected to the instance: The channel connecting us to the client, its
ip-address, and its ip-port.
- ${multiplexer_instance}::AddExitFilter cmdprefix
- Adds filter to be run when client socket generates an EOF condition. The
registered cmdprefix is called when a client socket of the multixer
signals EOF. If there is more than one exit filter command registered at
the instance they will be called in the order of registristation. Errors
thrown by an exit filter are ignored, but logged. Any result returned by
an exit filter is ignored. The command prefix is called as
- cmdprefix chan clientaddress clientport
- The arguments contain information about the client which signaled the EOF:
The channel connecting us to the client, its ip-address, and its
ip-port.
BUGS, IDEAS, FEEDBACK¶
This document, and the package it describes, will undoubtedly contain bugs and
other problems. Please report such in the category
multiplexer of the
Tcllib Trackers [
http://core.tcl.tk/tcllib/reportlist]. Please also
report any ideas for enhancements you may have for either package and/or
documentation.
KEYWORDS¶
chat, multiplexer
CATEGORY¶
Programming tools